Apparatus for irradiation of a moving product in an inert atmosphere

ABSTRACT

A treatment enclosure for irradiating a moving product which passes through said enclosure comprising an open treatment chamber housing a source of radiant energy, a pair of tunnels extending longitudinally from opposite sides of the chamber and an elongated inert gas injector channel, which opens into the enclosure a distance from the inlet tunnel end of the enclosure equal to at least ten times the smallest cross sectional dimension of the tunnel opening and which lies substantially parallel to the tunnel width, for directing inert gas at the moving product.

United States Patent 11 1 1111 Troue Apr. 30, 1974 54] APPARATUS FORIRRADIATION OF A 3,364,387 1/1968 Anderson 315/111 VI G PRODUCT IN ANINERT 3,11 1,424 1 H1963 LeClair ll7/93.31 2,887,584 5/1959 Nygard250/49.5 TE ATMOSPHERE v 2,763,609 9/1956 Lewis et al 204/159.l3 [75]Inventor: Harden Henry Trolie, Indianapolis, .7 5. 3 o ya et 313/2211nd. 3,150,281 9/1964 Bishay 313/221 [73] Assignee: Union CarbideCorporation, New FOREIGN PATENTS OR APPLICATIONS York, N.Y. 762,95312/1956 Great Britain 22 Filed: J ne .26 1972 1 u PrimaryExaminerWil1iam F. ODea PP 1 Assistant Examiner-P. Devinsky Attorney,Agent, or FirmE. Lieberstein [52] U.S. Cl 34/1, 117/9331, 204/l59.23,

250/492 [57] ABSTRACT ll'ilt. A treatment enclosure for irradiating a ig p [58] new of Search I 34/1 9 uct which passes through said enclosurecomprising an 204/159'1 1 17/9331 open treatment chamber housing asource of radiant 313/221 energy, a pair of tunnelsextendinglongitudinally from opposite sides of the chamber and anelongated inert [56] References cued gas injector channel, which opensinto the enclosure a UNITED STATES PATENTS distance from the inlettunnel end of the enclosure 3,600,122 8/1971 Coleman 117/47 A equal toat least ten times the smallest cross sectional 3,683,188 8/ 1972Hugonin 250/52 dimension of the tunnel opening and which lies sub-3.676.67 3 7/19 Co ema 117/9331 stantially parallel to the tunnel width,for directing 3,654,459 4 1972 Coleman 117/9331 inert gas-at the movingproduct 3,597,650 8/1971 Anderson et al. 315/111 3,418,155 12/1968Colvin et a1. 204/159.11 17 Claims, 12 Drawing Figures PATENTEUAPR 30 mmmin u 0F 4 i i i i i i APPARATUS FOR IRRADIATION OF A MOVING PRODUCT INAN INERT ATMOSPHERE This invention relates to apparatus for thecontinuous in-line irradiation treatment of the surface of a movingcoated product and more particularly to such apparatus for irradiatingthe surface of a moving coated product in a substantially inertatmosphere.

BACKGROUND OF THE INVENTION Subjecting a cross-linkable polymericcoating to radiant energy to improve its properties, particularly thesurface characteristics of the coating, has been an area of intensivestudy for many years. It has long been established that theeffectiveness of such irradiation as well as the curing speed may beenhanced by maintaining an inert atmosphere over the surface of thecoated product during the period of irradiation. This is especially truewhen electromagnetic energy or high energy electrons is used as theirradiating medium. Under con-- trolled laboratory conditions nodifficulty is experienced in maintaining an inert atmosphere over thesurface of the coated product. In fact, even in an industrial operationthe principal consideration is that of operating cost due primarily tothe high consumption of inert gas. It should be understood that anysaving in gas consumption, when realized over a period such as a year ina substantially continuousround-the-clock operation, translates intosubstantially reduced operating costs which can mean commercialviability for such processes.

For commercial acceptability the irradiation operation must take placeon the production line facility and therefore must be compatible withproduction line speeds which, depending upon the application, vary fromminimum speeds of about 60 feet per minute to present maximum speeds ofabout 600 feet per minute. A coated product moving at line speed carrieson its surface a thin film of air which must be substantially displacedby inert gas to permit effective surface curing when subjected toradiant energy. The displacement of such air must occur prior to theexposure time which is hereinafter defined as that interval of time inwhich a given coated product surface area is exposed to radiant energy.At a line speed of 600 ft/min. for a treatment chamber having forexample, a total length of 3 feet and an irradiation length of 1 foot,the chamber residence time would be 0.3 seconds and theexposure time 0.1seconds leaving a maximum time period of only 0.2 seconds to displacethe air film on the coated product surface.

In general, for a fixed inerting chamber geometry, the faster the coatedproduct travels through the chamber, the higher the inert gas flow ratemust be into the chamber to sustain an inert atmosphere. In addition,higher traveling speeds provide reduced time to attain a settling offlow patterns in the chamber and any differential concentration of inertgas existing along the surface of the coated product, particularly awide product, can result in a non-uniform cure. One may significantlyincrease the flow rate to forcibly sweep off atmospheric air which wouldotherwise be drawn in with the product or, alternatively reduce thetraveling speed. As a practical matter however, the traveling speed isfixed by the production line speed and the inerting system must becompatible with such speed. Moreover, the commercial user of the processwants to set the gas-flow rate only once and, for economy, at as low aflow rate as possible. Furthermore, not only is the production linespeed periodically varied to suit the particular application but alsoproduct size, particularly product width, varied periodically below amaximum value.

. Therefore, to satisfy commercial requirements the irradiation systemmust be capable of providing an acceptable uniform cure irrespective ofnormal production line variations in product width and product linespeed preferably using a single fixedtotal flow rate. Moreover, thesystem should be linearly scalable in dimensions and flow requirementsto permit predictable design of a unit for the uniform treatment of aproduct of any width and at any required line speed. Also, once thephysical system dimensions have been established for a maximum productwidth and line speed the system should provide equal treatment ofproducts of sub stantially reduced width dimensions and/or line speedswithout alteration of the system parameters.

Two recent patented publications namely French patents 2,058,090 and2,058,091 respectively, directly concern themselves with the presentsubject matter. Both patents describe various alternative designs formaintaining a relatively pure inert nitrogen atmosphere in a partiallyenclosed chamber through which the product passes for treatment. In theexamples given the travel speed is fixed at about 180 ft./min. and theproducts treated are limited to no greater than 15 inches in width. Inpractice, the product width will depend upon the commercial applicationand is accordingly varied on the production line to suit suchapplication. A product width of as much as inches is not uncommon.Although a relatively low gas flowrate is mentioned, there is noindication that the system design is linearly scalable to treatsubstantially wider products and/or narrower products at varying linespeeds.

OBJECTS OF THE INVENTION It is therefore the primary object of thepresent invention to provide an apparatus for continuous in-lineirradiation treatment of the coated surface of a moving product wherein'an inert gaseous atmosphere is maintained over the coated. productsurface during treatment.

It is another object of the presentinvention to provide apparatus formaintaining the surface of a moving coated product under a blanket ofinert gas during irradiation treatment thereof; which apparatus islinearly scalable in terms of the inert gas flow rate required to treatany product width at any desirable speed.

It is yet a further object to provide such radiation apparatus foruniformly treating a moving coated product while under a blanket ofinert gas which apparatus requires only a relatively low, substantiallyconstant, inert gas flow rate to sustain the inert atmospherenotwithstanding normal production line variations in product width orproduct speed below a predetermined maximum.

DRAWINGS exit tunnels respectively;

FIG. 7 illustrates in perspective a typical apparatus operated accordingto the present invention;

FIG. 8 is a longitudinal section taken along lines 88 of FIG. 7; v

FIG. 9 is a side view taken along lines 99 of FIG. 8.

DETAILED DESCRIPTION OF INVENTION Static systems for maintaining aninert gaseous environment about a workarea are well known. Theunderlying design concept basic to all of such systems, is to establishan inert gas flow pattern which will cause the air within the work areato be displaced by the inert gas, unit volume for unit volume, withoutpermitting the inert gas to intermix with the air. The difficultyresides in applying this rationale to a dynamic system where the coatedproduct is in motion relative to the work area. The moving coatedproduct tends to draw air into the work area disturbing the flowconditions and thereby creating turbulence. The problem is furtheraccentuated in chemical irradiation processes where only a slightpresence of oxygen at the coated product surface can inhibit surfacecuring.

FIG. 1 is a diagrammatic illustration of the assembly of the presentinvention. The product P which may represent a chemical coating or acoated substrate, of continuous length such as a web or of finite lengthsuch as for example a wallboard, is passed through a treatment enclosure10 where it is exposed to electromagnetic irradiation from a radiantenergy source (not shown). The radiant energy source is mounted in theradiation chamber 12 with appropriate optics (not shown) for directingthe electromagnetic radiant energy at the product P as it passesrelative thereto. Any source of electromagnetic radiant energy may beemployed although an internally cooled or non-cooled source ispreferred. If the source requires external cooling an opticallytransparent medium must be mounted to physically separate theirradiation zone 14 from the radiation chamber 12.

Internally cooled sources and non-cooled sources require no physicalseparation from the irradiation zone 14 and hence form an integral partof the treatment enclosure 10. A typical preferred internally cooledelectromagnetic radiation source is a plasma arc source as described inUS. Pat. Nos.'3,364,387 and 3,597,650 respectively. Typicalpreferrednon-cooled electromagnetic radiation sources are low pressureshortwave ultraviolet mercury tubes or germicidal lamps as disclosed inUS. Pat. application Ser; No. 266,122 filed concurrently herewith in thenames of C.L. Osborn and H.H. Troue and entitled Process.

The treatment enclosure 10 further includes an entrance or inlet tunnel16, an injector channel 18 through which inert gas is passed from aplenum chamber 20, and an exit tunnel 24. Inert gas is delivered to theplenum chamber 20 from an inert gas supply (not shown). Although anyinert gas may be used nitrogen is preferred.

The term tunnel for purposes of the present disclosure is defined as ahollow passageway of uniform cross-section which may either have aself-enclosed periphery or a partially enclosed periphery which becomessubstantially fully enclosed when the moving coated product is present.The length of the entrance tunnel 16 as well as the length of the exittunnel 24 should be as long as is practically permissable.

The location, geometry and orientation of the injec- I tor channel 18 iscritical in achieving a non-turbulent, non-mixing inert gas flow withinthe treatment enclosure 10 in such a manner that a gas flow below about500 cfh per each foot of tunnel width and preferably below about 400cfh/ft. of tunnel width is all that is necessary to achieve a uniforminert blanket over the coated surface of the moving product irrespectiveof product speeds up to about 600 fpm. Moreover once a gas flow rate hasbeen established as stated, for a given maximum tunnel width, thetreatment assembly will accomodate and uniformly blanket the coatedsurface of a moving product of any width up to said given tunnel widthand at any speed up to about 600 fpm.

The injector channel 18 must be located upstream from the inlet end 27of entrance tunnel 16 a distance of at least about 10 times the smallestcross-sectional dimension of tunnel 16. The height (H) of the channel 18should preferably be at least about four times greater than the width(W), i.e., the spacing between the side faces of the channel, as shownmore clearly in FIG. 2. The length (L) of the channel must be at leastsubstantially equal to thewidth of the product P and preferably equal tothe width of the entrance tunnel 16 and must be oriented substantiallyparallel to the tunnel width. Moreover, the channel 18 must also beoriented such that the inert gas is directed through the channel opening26 into the enclosure 10 at an included angle with respect to thelongitudinal axis of the enclosure 10 of from between 4590, preferablyThe distance between opening 26 and the moving product P should be assmall as normal product surface irregularities will allow. The height Hto width W relationship is not as critical is a porous medium is used tofill the channel spacing, but this makes the assembly somewhat moredifficult and moreexpensive to fabricate. Although the channel 18 isshown in FIG. 1 as a-pair of flat plates extending from a slot in theupper wall of tunnel 16, the slot itself may in fact represent thechannel provided the upper wall of tunnel 16 is of sufficient. thicknessto satisfy the desired height (H) to width (-W) relationship.

The gas supplied to the injector channel 18 flows Both the entrancetunnel 16 and the exit tunnel 2 4 are extensions of the radiationchamber 12 and serve to restrict the loss of inerting gas from theenclosure 10 as well as to direct the escaping inerting gas over thecoated surface of the product P in such a manner as to push off most ofthe air from the surface of product P before the product enters the areaof irradiation 14. A slight but significant pressure gradient existsbetween the injector channel opening 26 and the inlet end 27 of theentrance tunnel 16 which creates a back flow of inert gas out theentrance tunnel 16 so as to prevent an unacceptable quantity of air frombeing drawn in with the coated surface of product P. The exit tunnel 24serves in addition, as an escape path for the minor amount of air whichdoes enter the enclosure at the coated surface of product P and iscarried downstream with the coated product P. The inerting gas holdssuch air at the coated surface of product P and sweeps such air outthrough the exit tunnel 24 along with the exiting product as opposed toletting such air intermix with the inert atmosphere in chamber 12 andaccumulate to an unacceptable level.

The cross-sectional dimensions of the entrance and exit tunnels 16 and24 respectively are preferably selected to conform to thecross-sectional dimensionsof the coated product P to be treated. FIGS.4(a-c) illustrates three typical tunnel geometries for three typicalproduct shapes; viz., rectangular, triangular and cylindricalrespectively. In addition, as shown in FIGS. 5a and 5b the injectorchannel 18 and plenum chamber 20 respectively, should likewise conformin geometry to the cross-sectional geometry of the coated product P.This is also true for the radiation chamber 12 where uniform irradiationis desired about the entire periphcry of the product but does notmeanthat the radiant energy source need have such geometry since byappropriate optics in the chamber 12 one can accomplish the same result.

As stated hereinbefore the tunnel length (T l to the injector channelfor any tunnel configuration must be at least about ten times greaterthan the smallest crosssectional dimension of the tunnel. Hence, for arectangular tunnel geometry T 2 (10) T and T T where T Tunnel height TTunnel width; for a triangular tunnel geometry (FIG. 50) T 2 (10) T Tand for a cylindrical tunnel geometry (FIG. 5b) T 200) D "war'eu'imecross sect'ional 'dia' n i'eii of the cylinder. I

When the coated product P is present within the enclosure 10 and extendsthroughout the enclosure 10 the coated product itself may form thebottom of each tunnel. In such cases where the coated product P iscontinuously present, such as a web, the coated product P effectivelyforms the bottom of the chamber and no further bottom is required. Ingeneral, there should be no part of the irradiation area 14 physicallylower than the bottom exposed surfaces of the entrance and exit tunnelsl6 and 24 respectively. If it is necessary for some part of theirradiation area 14 to be lower than any of the lower surfaces of thetunnels then, in such instance, controlled leaks to the atmosphereshould be provided along such physically lower surface. In such instancethe nitrogen inerting gas will displace, downwardly, any air carried inwith the product P forcing such air to exit from such leaks.

The enclosure 10 geometry has been discussed above in relation to theuse of any inerting gas lighter than oxygen. It is to be understood thatby a proper choice of controlled leak locations, a gas heavier thanoxygen mental volumes V -V,',

could be used. Further, the chamber may also be physis cally reversed ifdesired.

The injector channel 18 assures an even flow distribution of inertinggas into the enclosure 10 with said flow directed substantially towardthe. surface of the moving coated product P and uniformly distributedacross the width of product P. The geometry of the injector channel 18as discussed hereinabove is intended to cause each substantially equalelemental volume of inerting gas to see essentially parallel flow pathsof equal length to the inlet opening of the entrance tunnel l6 andparallel flow paths of equal length to the outlet opening of the exittunnel 24. This is diagrammatically shown in FIG. 6 with V V,,representing substantially equal discrete elemental volumes of inert gasflowing toward opening 27 and V Vn representing substantially equaldiscrete elemental volumes of inert gas flowing toward opening 29.Discrete elemental volumes V V,, need not be equal to discrete ele-Also, the flow path length from the opening 26 to the inlet end 27 oftunnel 16 need not be equal to the flow path length from the opening 26to the'outlet end 29 of exit tunnel 24. .It is, however, significant tonote that the inert gaseous flow emerging from the injector channel 18cancels vectorially in all directions except in the longitudinaldirection. This phenomenon is the primary factor in achieving uniforminert blanketing over the coated product width and in establishing thelinearly scalable relationship between the inert gas flow and the tunnelwidth, in complete independence from the width of the coated product.Hence, as long as the tunnel openings are wide enough to accomodate thecoated product P any narrower coated product width, no matter hownarrow, may likewise be treated without altering the physical dimensionsor flow rate. Moreover, the product speed may be varied at will up toabout 600 fpm without affecting the treatment under the above notedconditions even though at the higher speeds the exposure time issubstantially shortened.

FIG. 7 illustrates in perspective a typical apparatus operated accordingto the present invention as it might appear installed on a productionline facility. A conveyor assembly 30 carries the coated product P tothe treatment enclosure 10 which is supported by frame 34. Pressureactuated cylinders 32 control the height of the tunnels of the treatmentenclosure 10 above the conveyor assembly 30. The cylinders 32 aremanually controllable to adjust the enclosure tunnel height as well asbeing automatically responsive to a passing product having an irregularor warped surface which is not to be .treated. When such a productpasses, the treatment enclosure 10 is automatically raised to apredetermined level while activating a shutter which passes beneath theradiation chamber 12. The shutter prevents the escape of radiant energyas will be explained more fully hereafter in connection with FIG. 8.

The radiation chamber 12 houses the electromagnetic radiation source andappropriate optics for directing the radiant energy toward theirradiating zone 14. It should be noted that in the typical system ofFIG. 7 the conveyor surface is being partially used as the bottomsurface of the treatment enclosure 10. Hence, the conveyor surfaces andthe coated product P, when it extends through the treatment enclosure10, forms an integral part of the enclosureacting as the bottom of thetreatment chamber. This is more clearly seen in FIGS. 8 and 9.

The injector channel 18 is preferably formed as an elongated slot in thewall of the plenum chamber 20. it must however bear the propergeometrical relationship discussed heretofore, i.e., it must bespacially oriented so as to direct the inert gas at the moving productat an included angle with the longitudinal axis of the enclosure of frombetween 45-90.

The channel 18 should, in addition, have a height to width relationshipof at' least about four to one. in the actual fabricated prototype theheight (H) is formed from k inch thick plate with a channel spacing ofH16 inch (W). Between the conveyor sections 38 and 40 and resting uponframe 34 isa platform assembly 42 which in conjunction with the conveyorsurfaces form the bottom surface of the treatment enclosure 10. Platformassembly 42 is comprised of a first sheet of Teflon with a number ofmirror sections 44 which are directly exposed to the radiation chamber12 and a second support sheet lying beneath thefirst sheet. The mirrorsections 44 of the platform assembly 42 reflect some of theelectromagnetic energy to the edges and underside of the passingproduct.

As stated before in connection with FIG. 7, when a product is presentedwhich is not to be treated because of its irregular surface orotherwise, the pressure actuated cylinders 32 are automaticallyactivated by means not shown thereby lifting the treatment enclosure toa predetermined height above the conveyor assemblies 38 and 40 andplatform assembly 42. Operating at such time in conjunction with thepressure actuated cylinders 32 is a further pressure actuated cylinder36. Cylinder 36 has a piston rod 46 connected at its free end to abracket 48 which is slidably mounted, through means such as ballbearings, on .a fixed shaft 52. The bracket 48 is also connected to ashutter assembly 50 also mounted for axial movement on fixed shaft 52.The bottom plate of the shutter assembly 50 represents the upper surfaceof exit tunnel 24. When the pressure actuated cylinder 36 is activatedthe piston rod 46 recedes causing the shutter assembly 50 to extendbeneath and enclose the radiation chamber 12. A cooling medium is passedthrough conduits 54 to cool the shut ter assembly 50.

FIG. 9 is a sectional view taken along the lines 99 of FIG. 8. Thetunnel passageway leading into the irradiation zone 14 is clearlyillustrated with its top surface represented by the plenum chambersurface 56 and its bottom surface represented by the platform assembly42. When the treatment enclosure 10 is lowered into its operatingposition the spacer plates 58 located on opposite sides thereof abutagainst the platform assembly 42 forming a pair of side walls for theentire treatment enclosure 10. A pair of side flaps (not shown) may alsobe used if controlled operating variation in tunnel height is desiredabove the first fixed-level determined by spacer plates 58.

In the apparatus shown in FIGS. 7-9 the internal enclosure width isapproximately 50 inches, i.e., a product of any width up to a maximum ofabout 48 inches is acceptable for treatment. The height of the tunnelsl6 and 24 respectively, in the enclosure operating position, is 3/8inch. The-length of the enclosure 10, end to end, is 60 inches. Thedistance from the inlet end of inlet tunnel 16 to the injector channelis approximately 18 inches while the distance from the injector channel18 to the radiation chamber 12 is approximately 6 inches. The radiationchamber 12 has a length of approximately 18 inches. The physicaldimensions herein given are illustrative only and may be scaled up ordown to suit a particular production facility. It should be kept in mindthat since the gas flow requirement is predictable, in keeping with thegas flow tunnel width relationship given heretofore, the physicaldimensions can thus be selected in accordance with available space onthe production facility.

When the above described apparatus is in operation, the inert gas flowpreferably nitrogen may be determined in accordance with therelationship betweenflow and tunnel width as set forth earlier, namely,about 400 cfh/ft. of tunnel width. Alternatively, a total flowcorresponding to a, normal product width and hence maximum tunnel width,for a particular commercial user, may be set without the necessity offurther adjustment for product width variations.

The following is set of examples where the total gas flow rate wasfixedly set at about 1500 cfh for products of widely varying widths upto a maximum of about 48 inches and'widely varying speeds from fpm to500 fpm. The thickness of the product varied up to A inch.

A coating composition was prepared from 50g acrylated epoxidized soybeanoil, 30g hydroxyethyl acrylate, and 20g neopentylglycol diacrylatefTo10g aliquots of this composition was added 0.01 mole of varioussensitizers. The coating was applied at a wet film thickness of2 mils toBonderite No. 37 steel panels and irradiated at the indicatedexplosures, under nitrogen blanketing, using a Plasma Arc RadiationSource. Results of analysis of the cured films are listed below:

trate and lift film from metal substrate I claim:

1. Apparatus for in-line irradiation treatment of a moving productcomprising:

a. a first and second tunnel of substantially uniform cross section eachhaving an inlet end and an outlet end;

b. a treating chamber having at least one treating source mountedtherein, said chamber being located intermediate the outlet end of saidfirst tunnel and the inlet end of second tunnel and forming therewith aa continuous enclosure;

0. means for maintaining a substantially inert atmosphere at the surfaceof said moving product comr s n s A 1. an elongated gas'injctor c'hannlhaviiig a first open end communicating with said enclosure and locatedintermediate said first tunnel opening arid said treatment chaifibefiridfufiher located from the inlet and of said first tunnel a' distanceequal to at least about ten times the smallest cross-sectional dimensionof said first tunnel.

' said first open end having a length at least substantially equal tothe Width of said product with the longer axis of said opening directedsubstantially parallel to the width of said first tunnel;

2 a plenum chamber connected to a second open end of said channel; and

3 a source of inert gas for continuously introducing inert gas into saidplenum chamber.

2. Apparatus as defined in claim 1 wherein said gas injector channel isspacially oriented to direct said inert gas toward said product at anincluded angle of from between 45 90 with respect to the longitudinalaxis of said enclosure.

3. Apparatus as defined in claim 2 wherein said gas injector channel isthe sole means for introducing inert gas into said enclosure.

- 4. Apparatus as defined in claim 3 wherein the first open end of saidchannel is disposed in relatively close proximity to said movingproduct.

5. Apparatus as defined in claim 1 wherein said gas injector channel isa slotted groove formed in the upper wall of said first tunnel and hasparallel side faces.

6. Apparatus as defined in claim 5 wherein said injector channel has aheight at least four timesgrea'ter than the channel width.

7. Apparatus as defined in claim 6 wherein said first and second tunnelshave a cross-sectional geometry substantially conforming to thecross-sectional geometry of said product.

8. Apparatus as defined in claim 7 wherein the smallest cross-sectionalarea of said plenum chamber is at least about ten times greater than thelongitudinal cross-sectional area of said channel.

9. Apparatus as defined in claim 8 wherein said inert gas is nitrogen.

11. Apparatus as defined in claim 10 wherein said enclosure has a bottomplanar surface upon which the product passes representing the bottomside of said first tunnel, said treating chamber and said second tunnelrespectively.

12. Apparatus as defined in claim 10 wherein said product is acontinuous web which once extended through said enclosure forms thebottom surface thereof.

13. Apparatus as defined in claim 11 wherein said bottom surfaceincludes at least one relatively small aperature communicating with theatmosphere. V r

14. Apparatus as defined in claim 13 further comprising means forraising said enclosure a predetermined distance above said product inresponse to a product which is not to be treated and means operating incon junction therewith for passing a shutter beneath said treatmentchambe'rto prevent the escape of radiant energy.

15. Apparatus as defined in claim 14 wherein said enclosure furthercomprises. means for controllably adjusting the height of said tunnels.

16. Apparatus as defined in claim 1 wherein said treating source is aninternally cooled plasma arc source.

17. Apparatus as defined in claim 1 wherein said treating sourceconsists of at least one non-cooled low pressure shortwave ultravioletmercury tube or germicidal tube.

UNITED STATES PATENT OFFiCE CERTIFICATE OF CORRECTION Patent No. 3,807,052 Dated April 30-, 197 4 Inventor(s) It is certified that errorappears in the above-identified patent and that said Letters Patenthereby eerrectecl as shown below:

In Claim 5, line 1, the numeral 1 should read 4.

Signed and sealed this 15th day of October 1974.

(SEAL) Attest:

McCOY M; GIBSON JR. 0. MARSHALL DANN Commissioner of Patents AttestingOfficer

1. Apparatus for in-line irradiation treatment of a moving productcomprising: a. a first and second tunnel of substantially uniform crosssection each having an inlet end and an outlet end; b. a treatingchamber having at least one treating source mounted therein, saidchamber being located intermediate the outlet end of said first tunneland the inlet end of second tunnel and forming therewith a a continuousenclosure; c. means for maintaining a substantially inert atmosphere atthe surface of said moving product comprising 1 an elongated gasinjector channel having a first open end communicating with saidenclosure and located intermediate said first tunnel opening and saidtreatment chamber and located from the inlet end of said first tunnel adistance equal to at least about ten times the smallest cross-sectionaldimension of said first tunnel, said first open end having a length atleast substantially equal to the width of said product with the longeraxis of said opening directed substantially parallel to the width ofsaid first tunnel; 2 a plenum chamber connected to a second open end ofsaid channel; and 3 a source of inert gas for continuously introducinginert gas into said plenum chamber.
 2. Apparatus as defined in claim 1wherein said gas injector channel is spacially oriented to direct saidinert gas toward said product at an included angle of from between 45* -90* with respect to the longitudinal axis of said enclosure. 3.Apparatus as defined in claim 2 wherein said gas injector channel is thesole means for introducing inert gas into said enclosure.
 4. Apparatusas defined in claim 3 wherein the first open end of said channel isdisposed in relatively close proximity to said moving product. 5.Apparatus as defined in claim 1 wherein said gas injector channel is aslotted groove formed in the upper wall of said first tunnel and hasparallel side faces.
 6. Apparatus as defined in claim 5 wherein saidinjector channel has a height at least four times greater than thechannel width.
 7. Apparatus as defined in claim 6 wherein said first andsecond tunnels have a cross-sectional geometry substantially conformingto the cross-sectional geometry of said product.
 8. Apparatus as definedin claim 7 wherein the smallest cross-sectional area of said plenumchamber is at least about ten times greater than the longitudinalcross-sectional area of said channel.
 9. Apparatus as defined in claim 8wherein said inert gas is nitrogen.
 10. Apparatus as defined in claim 9wherein the cross-sectional geometry of said channel substantiallyconforms to the cross-sectional geometry of each of said first andsecond tunnels.
 11. Apparatus as defined in claim 10 wherein saidenclosure has a bottom planar surface upon which the product passesrepresenting the bottom side of said first tunnel, said treating chamberand said second tunnel respectively.
 12. Apparatus as defined in claim10 wherein said product is a continuous web which once extended throughsaid enclosure forms the bottom surface thereof.
 13. Apparatus asdefined in claim 11 wherein said bottom surface includes at least onerelatively small aperature communicating with the atmosphere. 14.Apparatus as defined in claim 13 further comprising means for raisingsaid enclosure a prEdetermined distance above said product in responseto a product which is not to be treated and means operating inconjunction therewith for passing a shutter beneath said treatmentchamber to prevent the escape of radiant energy.
 15. Apparatus asdefined in claim 14 wherein said enclosure further comprises means forcontrollably adjusting the height of said tunnels.
 16. Apparatus asdefined in claim 1 wherein said treating source is an internally cooledplasma arc source.
 17. Apparatus as defined in claim 1 wherein saidtreating source consists of at least one non-cooled low pressureshortwave ultraviolet mercury tube or germicidal tube.